View source for Arduino: RTC DS3231 PC Sync

Sumber: http://playground.arduino.cc/Code/time


==Siapkan Library==

Download dari

* http://playground.arduino.cc/uploads/Code/Time.zip

Extrak

 cd /usr/share/arduino/libraries/

atau

 cd ~/Arduino/libraries

 wget http://playground.arduino.cc/uploads/Code/Time.zip
 unzip Time.zip
 cd Time
 gedit DateStrings.cpp 

Tambahkan di

 char   > char  const
 PGM_P  > PGM_P const

==Code==

 #include "Wire.h"
 #include <Time.h>  
 
 #define TIME_MSG_LEN  11   // time sync to PC is HEADER followed by Unix time_t as ten ASCII digits
 #define TIME_HEADER  'T'   // Header tag for serial time sync message
 #define TIME_REQUEST  7    // ASCII bell character requests a time sync message
 
 #define DS3231_I2C_ADDRESS 0x68
 // Convert normal decimal numbers to binary coded decimal
 byte decToBcd(byte val)
 {
   return ( (val / 10 * 16) + (val % 10) );
 }
 // Convert binary coded decimal to normal decimal numbers
 byte bcdToDec(byte val)
 {
   return ( (val / 16 * 10) + (val % 16) );
 }
 void setup()
 {
   Wire.begin();
   Serial.begin(9600);
   
   // set the initial time here:
   // DS3231 seconds, minutes, hours, day, date, month, year
   // setDS3231time(30,33,9, 2 ,28,11,16);
 }
 void setDS3231time(byte second, byte minute, byte hour, byte dayOfWeek, byte
                    dayOfMonth, byte month, byte year)
 {
   // sets time and date data to DS3231
   Wire.beginTransmission(DS3231_I2C_ADDRESS);
   Wire.write(0); // set next input to start at the seconds register
   Wire.write(decToBcd(second)); // set seconds
   Wire.write(decToBcd(minute)); // set minutes
   Wire.write(decToBcd(hour)); // set hours
   Wire.write(decToBcd(dayOfWeek)); // set day of week (1=Sunday, 7=Saturday)
   Wire.write(decToBcd(dayOfMonth)); // set date (1 to 31)
   Wire.write(decToBcd(month)); // set month
   Wire.write(decToBcd(year)); // set year (0 to 99)
   Wire.endTransmission();
 }
 void readDS3231time(byte *second,
                     byte *minute,
                     byte *hour,
                     byte *dayOfWeek,
                     byte *dayOfMonth,
                     byte *month,
                     byte *year)
 {
   Wire.beginTransmission(DS3231_I2C_ADDRESS);
   Wire.write(0); // set DS3231 register pointer to 00h
   Wire.endTransmission();
   Wire.requestFrom(DS3231_I2C_ADDRESS, 7);
   // request seven bytes of data from DS3231 starting from register 00h
   *second = bcdToDec(Wire.read() & 0x7f);
   *minute = bcdToDec(Wire.read());
   *hour = bcdToDec(Wire.read() & 0x3f);
   *dayOfWeek = bcdToDec(Wire.read());
   *dayOfMonth = bcdToDec(Wire.read());
   *month = bcdToDec(Wire.read());
   *year = bcdToDec(Wire.read());
 }
 void displayTime()
 {
   byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
   // retrieve data from DS3231
   readDS3231time(&second, &minute, &hour, &dayOfWeek, &dayOfMonth, &month,
                  &year);
   // send it to the serial monitor
   Serial.print(hour, DEC);
   // convert the byte variable to a decimal number when displayed
   Serial.print(":");
   if (minute < 10)
   {
     Serial.print("0");
   }
   Serial.print(minute, DEC);
   Serial.print(":");
   if (second < 10)
   {
     Serial.print("0");
   }
   Serial.print(second, DEC);
   Serial.print(" ");
   Serial.print(dayOfMonth, DEC);
   Serial.print("/");
   Serial.print(month, DEC);
   Serial.print("/");
   Serial.print(year, DEC);
   Serial.print(" Day of week: ");
   switch (dayOfWeek) {
     case 1:
       Serial.println("Sunday");
       break;
     case 2:
       Serial.println("Monday");
       break;
     case 3:
       Serial.println("Tuesday");
       break;
     case 4:
       Serial.println("Wednesday");
       break;
     case 5:
       Serial.println("Thursday");
       break;
     case 6:
       Serial.println("Friday");
       break;
     case 7:
       Serial.println("Saturday");
       break;
   }
 }
 
 void loop(){    
   if(Serial.available() )
   {
     processSyncMessage();
   }
   if(timeStatus() == timeNotSet)
     Serial.println("waiting for sync message");
   else    
      // digitalClockDisplay();  
       displayTime();
   delay(1000);
 }


 void digitalClockDisplay(){
   // digital clock display of the time
   Serial.print(hour());
   printDigits(minute());
   printDigits(second());
   Serial.print(" ");
   Serial.print(day());
   Serial.print(" ");
   Serial.print(month());
   Serial.print(" ");
   Serial.print(year());
   Serial.println();
 }
 
 void printDigits(int digits){
   // utility function for digital clock display: prints preceding colon and leading 0
   Serial.print(":");
   if(digits < 10)
     Serial.print('0');
   Serial.print(digits);
 }
 
 void processSyncMessage() {
   // if time sync available from serial port, update time and return true
   while(Serial.available() >=  TIME_MSG_LEN ){  // time message consists of header & 10 ASCII digits
     char c = Serial.read() ;
     Serial.print(c);  
     if( c == TIME_HEADER ) {      
       time_t pctime = 0;
       for(int i=0; i < TIME_MSG_LEN -1; i++){  
         c = Serial.read();          
         if( c >= '0' && c <= '9'){  
           pctime = (10 * pctime) + (c - '0') ; // convert digits to a number    
         }
       }  
       setTime(pctime);   // Sync Arduino clock to the time received on the serial port
       // set the initial time here:
       // DS3231 seconds, minutes, hours, day, date, month, year
       setDS3231time(second(),minute(),hour()+7, 5 , 7, 6, 18);
     }  
   }
 }

==PC Sync==

Lakukan

 date +T%s\n > /dev/ttyACM0

Untuk mensinkronisasi waktu

==Referensi==

* http://playground.arduino.cc/Code/time